Glass base grid



D. R. KERSTETTER ET'AL June 2, 1959 GLASS BASE GRID FiledSept. 1, 1954 ATTORNEY United States Patent 2,889,483 GLASS BASE GRID bonald R. Kerstetter and Paul H. Sassam'an, Emporium, Pa.,- assignors to Sylvania Electric Products Inc., a corporation of Massachusetts 4 1 Application September 1, 1954, Serial No. 453,488 2 Claims. (01. 313-299) The present invention relates to electron discharge devices, and more particularly to an improved construction for grid electrodes employed in these devices.

I The grid electrodes known in the prior art usually comprise a plurality of small dimensional lateral wires which are supported parallel to one another by larger wire side rod elements. .In view of the increased exactness, compactness, and size required for present day tubes, it is becoming more difiicult to satisfactorily make and mount tube grid electrodes. These difiiculties are due to the inherent weaknesses and size of the tube components.

One type of grid construction devised to obviate this weakness and still retain the exactness required for premium quality, while using small dimensional components, is one which comprises a plurality of parallel lateral wires supported by rigid insulating support memhers. The extremities of these lateral wires are secured to the insulating support members by fusion. This type of grid structure entails costly and additional production fabricationsteps, and does not alleviate the necessity of handling very thin and weak, small dimensional, lateral WII'CS.

An object of this invention is to obviate the aforesaid difiic'ulties.

Another object is to provide for a novel and improved structure for use in electron discharge devices whereby the lateral conductors are rigidly and accurately secured in their correct positions. I

IA further object is to provide for a unitary multiple electrode structure which can be accurately fabricated and easily mounted in a tube electrode assembly.

A still further object of this invention is to provide for an improved beam type electron discharge device which employs a pre-formed, pre-aligned unitary multiple grid assembly.

A still further object of this invention is to provide for an improved beam type electron discharge device which employs a pre-formed, pre-aligned unitary multiple grid assembly.

A still further object is to provide for an electron discharge device electrode formed by the deposition of a conductive coating on a photo-sensitive etched insulating member.

Briefly, the present invention relates to an improved electrode for tubes wherein the electrode is in the form of a conductive sheath integrally associated and co-extensive with one major surface of an insulating support member. Both major surfaces of this support member may be integrally associated with conductive sheaths, thereby providing for a pre-formed unitary multiple electrode structure.

The novel features that are considered characteristic of my invention are set forth with particularity in the appended claims. The invention itself will be more readily understood from the following description, reference being made to the accompanying drawings wherein:

Fig. 1 is a perspective view of one type of grid elec- 2 trode assembly embodying the construction of my invention.

Fig. 2 is a sectionalized view along line 22 of the structure shown in Fig. l.

Fig. 3 is a perspective view of another type of grid electrode assembly embodying the construction of my invention.

Fig. 4 is a view, partly in section, of an electron discharge device embodying a grid electrode assembly made in accordance with my invention.

As shown by Fig. l, the grid assembly 12 comprises two major components, namely a base member 14.and a grid electrode 16. The base member 14, which is made of an insulating material such as glass, has support appendages 18 at both of its vertical axial extremities for facilitating mounting and securing the grid assembly within the envelope of a tube. The center section of the. base member 14 has a plurality of parallel apertures 20 of pre-detennined size to allow passage of electrons transversely through the member. 16 is a conductive sheath integrally associated with a major surface 24 of the base member 14. This grid else-- trode 16. is substantially coextensive with the major surface of the base member 14, except for the region definedby and close to the support appendages 18. The lateral conductors 26 of the grid completely cover the area surrounding the apertures 20 in the base member 14. Connected to the grid 16 at one of its extremities is a conductive lead tab 28, which will provide for anelectrical connection for the grid to its source of potential. This lead tab is fused or welded to the lower portion of the grid.

As shown clearly in Fig. 2, the grid electrode assembly 12 may comprise the base member 14 and two grids, 16 and 22. This structure embodies a unitary multiple grid assembly. In this instance, the grids 16 and 22 are both integrally associated with the base member 14, one grid being associated and substantially co-extensive with each major face of the base member. 30 supply the operating potential for the grids 16 and 22.

Fig. 2 also clearly shows the relationship of the grid lateral conductors 26 and 32 of the two grids 16 and 22 with respect to each other. The apertures 20 not only extend through the base member but also through the,

grids 16 and 22, thereby providing for absolute alignment of the lateral conductors of one grid with respect to the other. However, the grid lateral conductors 26 and 32 need not be laterally aligned with respect to each other so that the lateral conductors of one grid are in the same horizontal plane as the lateral conductors of the other grid, since the apertures 20 may be at an angle other than to the major faces of the base member.

The multiple grid electrode assembly may be of a shape other than flat. The assembly may, for example, be circular as shown in Fig. 3. A circular insulating base member 34, having supporting projections 40 and 42 thereon, and apertures 44 therein may be used in conjunction with an enclosed grid 36 and an exterior grid 38. These grids are integrally associated with the inner and outer major faces of the base member, respectively. I The grids are electrically connected to their source of potential by their lead tabs 48, only the tab connected to the outer grid being visible in Fig. 3.

Fig. 4 illustrates an electron discharge device 34 having mounted therein between insulating spacers 44 and 46, a cathode 36, two unitary multiple-grid assemblies 12 and 38, and an anode 40. This tube could be used as a single beam type power amplifier, or if two electrically insulated anodes are mounted to cooperate respectively one with each set of electrodes, a duo-tetrode beam type power amplifier is provided, If only one grid sheath is The grid electrode The lead tabs 28 andv integrally associated with one major face of the base member 14, which base member is shown clearly in Fig. 1, a tube may embody either a single-triode or duotn'odetype mountassembly. When the grid lateral conductors 26 and 32 are not laterally aligned so that the lateral conductors nearest the cathode do not shade'the lateral conductors of the other grid, the tube may embody either a conventional single or duo-tetrode mount assembly.

Numerous methods may be employed to make the grid structures of this invention. One of the most accurate and efiicient processes involves the formation of the base member 14 by photo-etching means. Briefly, this process entails coating an article of glass, which has been pre-cut to the exterior size and shape desired, with a photosensitive material, such as silver chloride. The next steps are the formation of a positive design on the photo-sensitive material by the application of light to those areas not covered by a mask of pie-determined configuration, and a subsequent dissolving of the unexposed photo-sensitive material. The glass base is then etched over the unexposed areas to produce apertures therein, thus providing for the formation of a glass grid support of the type embodied in this invention. To complete the grid assembly, a deposit of metal is applied to the major surfaces of the glass member by electroplating or other means for providing the conductive sheath defining the grid electrodes.

In addition to the simplicity of production and accuracy attained in making electrodes of the type described in the present invention, the grid structure itself is rigid, strong, and easily mountable in an electrode assembly. When two metallic sheaths are integrally associated with both major surfaces of the insulating base member, the structure affords a rigid pre-formed multiple grid as sembly. This rigidity provides for a reduction in the number of tubes rejected for microphonism, since it ohviates vibrational movement of the grids under tube operating conditions.

Another advantage in the unitary multiple grid as sembly is the permanent horizontal alignment of the lateral conductors of one grid with respect to the lateral conductors of the other grid. This permanent alignment reduces lossesin the manufacture of line-up type tubes due to misalignment of grids, which misalignment causes high screen current. It also avoids the necessity for fabrication of a special anode which would facilitate observance of the grids during the line-up operation. Such specially constructed anode usually includes an observation Window cut into the center portion thereof.

The rigidity of a grid electrode made in accordance with my invention markedly diminishes production losses in the manufacture of tube grid components. These losses, amongst others, were due to the inherent weaknesses of conventional lateral wire type grids, misplacement and jamming of lateral wires, and bowing of the grid side rods.

The invention has been described herein particularly with relation to grid electrodes for electron discharge devices, but it is to be understood that other electrodes in these devices may also be applicable to the present type of structure. It is also to be understood that the invention is not limited to the exact construction shown, or to the type of materials used as an example.

The novel features of the present invention are set forth with particularity in the appended claims.

We claim as our invention:

1 An electrode assembly for an electron discharge device comprising in combination, a base member of dielectric material having a plurality of parallely aligned straight slots extending therethrough perpendicular to the major faces of said member, and a pair of slotted con ductive electrodes integrally associated with both major faces of said base member, the slots in the electrodes bei'n'g in register with the slots in the base member.

2. An electrode assembly for an electron discharge d'e'' vice comprising in combination, a base member of di'-' electric material having a plurality of parallelyaligned straight slots'ext'endin'g therethrough perpendicular to'the major faces of said member, and a pair-of slotted eon-f ductive electrodes integrally associated with both major faces of said base member, the slots in the electrodes being in register with the slots in the base member and extending uninterruptedly substantially from one side edge of said member to the opposite side edge.

References Cited in the file of this patent UNITED STATES PATENTS 7 

